Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 25, 2008
Publication Date: April 1, 2009
Citation: Alva, A.K. 2009. Effects of various pre-plant and in-season nitrogen management practices for potatoes on plant and soil nitrogen status. Communications in Soil Science and Plant Analysis. 40: 649-659. Interpretive Summary: Potato crop is very sensitive to adequate nitrogen availability at the right amount at the right growth stage. This is particularly important for optimal processing qualities. Although considerable research has been done on evaluation of nitrogen nutrition of potatoes in the Pacific Northwest, the changing production practices with use of recently released cultivars and emphasis on minimizing nitrate leaching losses thus required renewed interest and the need to conduct new research to develop nitrogen best management practices. In this study, monitoring of petiole nitrate concentration and soil extractable nitrate and ammonium concentrations were evaluated for potatoes grown in a sandy soil with different rates of pre-plant and in-season nitrogen applications. Ranger Russet potato cultivar was used in this study. With different nitrogen management practices, tuber yields varied from 54 to 64 and 78 to 90 metric tones per hectare in 2004 and 2005, respectively. Petiole nitrate concentrations were lower in 2005 as compared to those in 2004, particularly during the later growing stage. Available soil nitrogen content was greater in 2004 than that in 2005. Increased availability of soil nitrogen during the later growing period can adversely impact the tuber yield and quality. This might explain, in part, greater tuber yield and greater proportion of large size tubers (>340 g weight) in 2005 as compared to those in 2004.
Technical Abstract: Adequate availability of nitrogen (N) to satisfy potato crop N requirement is critical for production of optimal tuber yields with high processing qualities, which will contribute to maximum net returns. The agroclimatic conditions in the Columbia Basin region in the Pacific Northwest (PNW) supports high potato tuber yields with high processing qualities. Best management of N fertilization is important to increase N uptake efficiency and to minimize N losses. Monitoring soil and petiole N provides a basis to evaluate available N in the soil and N status in the plants. This study was conducted on a Quincy fine sand (mixed, mesic Xeric Torripsamments; >95% sand) using ‘Ranger Russet’ potato cultivar. Potato followed by two years of sweet corn rotation was adapted in this study. Treatments included the following pre-plant (PP) + in-season (IS) N rates in kg/ha: (i) 56+280; (ii) 112+224; (iii) 112+336, in 2004 or 112+112, in 2005. The IS N was applied in five equally divided doses at 2 week intervals, 3 weeks after seedling emergence. An additional treatment was included with treatment (ii) N rates, except that IS N was delivered in 10 weekly applications. Total tuber yield ranged from 54 to 64, and 78 to 90 Mg ha-1, respectively in 2004 and 2005. In 2004, during the first 65 days after emergence (DAE), petiole NO3 concentration was lower in the treatment (i) than that in the other treatments. This difference was not evident in 2005. The petiole NO3 concentrations were lower in 2005 than that in 2004, particularly during later part of the growing period. Soil available N (NO3-N+NH4-N in the top 30 cm depth) concentrations were also greater in 2004 than those in 2005. Soil N appeared to increase towards the end of the growing season in 2004, which has negative effects on tuber yield and quality. Across all treatments, total tuber yield and that of >340 g size grade tubers were greater in 2005 than that in 2004.